also es funktioniert jetzt. drop am besten mal deine procedure und kopier folgende rein:

 CREATE OR REPLACE procedure download_my_file(p_file in number) as
	v_mime  varchar2(255);
	v_length  number;
	v_file_name varchar2(2000);
	Lob_loc  BLOB;
BEGIN
	select mime_typ, blob_content, name,dbms_lob.getlength(blob_content)
		into v_mime,lob_loc,v_file_name,v_length
		from file_subjects
		where id = p_file;
              --
              -- set up HTTP header
              --
                    -- use an NVL around the mime type and 
                    -- if it is a null set it to application/octect
                    -- application/octect may launch a download window from windows
                    owa_util.mime_header( nvl(v_mime,'application/octet'), FALSE );

                -- set the size so the browser knows how much to download
                htp.p('Content-length: ' || v_length);
                -- the filename will be used by the browser if the users does a save as
                htp.p('Content-Disposition: attachment; filename="' || v_file_name || '"');
		-- close the headers		
                owa_util.http_header_close;
		-- download the BLOB
		wpg_docload.download_file( Lob_loc );
end download_my_file;

Nicht vergessen:
grant execute on download_my_file to public


PS: Heißt deine Tabellenspalte extra MIME_TYP und nicht MIME_TYPE?


MfG
Andreas